The DA Index® or index ΔA is an index of the state of maturation of the fruit based on the difference of absorbance at two wavelengths: one at which has the maximum absorption by chlorophyll-type and a second, used as a reference , chosen to have the minimum change in absorbance during the whole period of fruit ripening.
The value of DA is proportional to the amount of chlorophyll present in the fruit. Since this tends to fall off during maturation, the DA Index® will tend to decrease over time, reaching values close to 0 for fruits already overly ripe for commercial use.
Instrument for the measurement of the DA
The reference values for the collection and consumption vary from species to species ..